Hot water / Central heating programmer problems.

[Milesy]

My father in law changed the front and back plate of a drayton programmer and is certain every wire is
wired exactly the same way they were. Something is not right though.

The upstairs hot water boiler is working ok, but the downstairs central heating boiler is not working.

this is how the manual says the circuit works... although it does not specify how to wire it
up when including a remote thermostat in the circuit (the thermostat manual doesnt say either)

http://www.chrismiles.pwp.blueyonder.co.uk/therm1.gif

And here is how it is currently wired.

http://www.chrismiles.pwp.blueyonder.co.uk/therm2.gif

First question:

the hot water works fine so I am assuming that the HW is working fine, although I am confused to why
the live wire going upstairs is connected to the OFF terminal rather than the ON terminal. I know this
was *definately* correct as the ON terminal is screwed right down and has never been opened to allow
a wire in.


Second question:

I assume when the second relay kicks in and switches to the ON position, current is sent up the yellow
wire to the "call for heat" terminal at the thermostat, should this yelllow wire connect into the L terminal
or the "call for heat" terminal on the thermomstat?

I assume it doesnt really matter what way round yellow and red are anyway? Can I do this.

At the programmer... take the yellow as the switched live to the L terminal on the thermomstat, then
take the red wire back up to behind the programmer and connect to the red wire for the boiler using
a 13amp connector block just like shown on the picture ?

Third question:

The theromstat says it is essential to have a neutral connection, at the theromstat the blue wire coming
from the programmer is connected to the N terminal, however at the programmer it is not connected to
the other N terminal as you can see in the picture, and like I said my father in law is absolutely certain
thats how it was wired.

Please help if possible

many thanks

Chris

 

[Paul Barker]

As you have sufficient wires for a thermostat with a preheat coil then use the neutral, but this goes all the time to a neutral supply. Many roomstats whith a preheat facility absolutely require this to function, I prefer stats where this is optional so that if there isn't a neutral wire already there it is less obtrusive. It is a useless function that makes no practical difference.

The usual mistake with Y plan is not to connect the dhw stat make on no call for heat to the hot water off on the programmer and the greay on the mid position valve. This is the only way that the heating will come on when hot water is satisfied.

Another common m,istake is to miss out a feed link within the wiring system, and sometimes a neutral is omitted giving odd performance in some functions only. The numbering systems in the control centre vary between manufacture, but the colouring of mid position valve flying leads is universal.

When I have to rip one apart and start again I always follow the Honeywell number system. Then at least I know where I am.

Check that first and report back.

 

[fireman22]

what water boiler have you got upstairs? do you mean the tank with an imm element? or is the cable going to a tank stat clamped to the side of the tank or to a seperate boiler

 

[Milesy]

apologies... its an imersion tank up stairs. with a electrical "drayton" brand "mid point valve"

 

[Milesy]

behind the programmer there are only 4 sets of wires.

one incoming live.
one going to the boiler in the kitchen cupboard
one going to the immersion tank area upstairs
one going to the thermostat (3 wire)

the boiler never had a permanant live from what I can see,
so does the boiler *just* do my central heating and not my hot water?

i know its defo a fully pumped system, but is the boiler still supposed to be used for both HW and CH ?

 

[Paul Barker]

This is going to be hard work.

To start with, you should have either a mid position valve, probably in the airing cupboar with three pipes to it. Can you confirm? Or do you have two zone valves with two pipes each?

Secondly you should have a wiring centre usually near to the valves.

Thirdly you should have a cylinder thermostat about third way up cylinder strapped round it.

We know that you have a roomstat a programmer and a boiler.

Fill in the blanks and then we will proceed.

 

[Milesy]

I have a drayton mid position valve.

Yes there is a wiring centre near it with a high voltage sticker on it.

Yes there is a drayton device strapped onto the tank.

 

[fireman22]

well if all your father in law has done is move wires around in the programmer, then, the neutral of the wall stat should go to the neutral terminal in the programmer not the hot water on terminal, and move the red from the hw off terminal to the hot water on terminal (now empty) and it should work
i am guessing the cable you have marked kitchen boiler comes from the wiring centre upstairs can you confim this? or does it go straight to the boiler clipped surface so you know for sure

 

[Milesy]

thats part of the problem.... the red coming from the HW off was definately always on there...... the on terminal is screwed right down showing that no wire has ever been put into it.

 

[fireman22]

could he have tightened it up after taking out the wire tho?

 

[fireman22]

was there always a connector block inside the programmer ?

 

[Milesy]

he didnt... he just screw out the wires took the back plate off, put the new one in.

so the old back plate is sitting on the work surface after having the wires removed and the ON terminal is screwed tight down, with no markings on the screw head even showing it has even been touched with a screwdriver (the other ones do)

 

[Milesy]

yes there was a connector block.

with the red wire coming the thermostat connected to the brown wire going into the boiler in the kitchen.

 

[fireman22]

but hang on your drawing shows both on terminals with wires in,???

 

[Milesy]

because it is not wired up properly

thats what I am trying to fix